U.S. Pat. No. 3,423,256 discloses a process for co-nitrating a mixture of an aliphatic polyol and trimethylolethane with concentrated aqueous nitric acid. The triethylene glycol required in the present invention has an ether linkage and therefore is not an aliphatic polyol. U.S. Pat. No. 4,352,699 discloses a process of co-nitrating a mixture of trimethylolethane and diethylene glycol with a mixture of sulfuric and nitric acids. The co-nitration process of the present invention utilizes triethylene glycol instead of diethylene glycol, and the nitration of triethylene glycol is known to produce an unstable spent acid, a problem not present with diethylene glycol. Thus, U.S. Pat. No. 4,352,699 neither suggests nor implies that triethylene glycol and trimethylolethane could be co-nitrated successfully.
Trimethylolethane and triethylene glycol have been nitrated separately to form trimethylolethane trinitrate and triethylene glycol dinitrate that then are blended together in desired proportions. This method, however, necessitates separate production lines for each component. In addition, the nitration of triethylene glycol does not produce a stable spent acid, and thus the nitration product requires drowning with water for safety reasons. In addition to creating large amounts of triethylene glycol dinitrate contaminated wastewater, the excess nitric and sulfuric acids cannot readily be recovered and recycled.
Accordingly, an object of this invention is to provide a more efficient method of producing mixtures of trimethylolethane trinitrate and triethylene glycol dinitrate.